Syntax and parsing of unknown pseudo-classesIan HicksonCSS 3 ModuleW3C SelectorsNextSyntax and parsing of unknown pseudo-classes and pseudo-elementsPreviousSyntax and parsing of new pseudo-elementsTest #251 of 296TestingSyntax and parsing of unknown pseudo-classesID160Date2001-11-20Revision1.0

This line should have a green background.

p { background: lime; }
p:subject { background: red; } /* this is not valid CSS, and if UAs
implemented the experimental :subject pseudo-class they should have
used the :-vnd-ident syntax. */
<p xmlns="http://www.w3.org/1999/xhtml">This line should have a green background.</p>